I don't think a UBI outside of Steemit is sustainable. Many Countries are deeply in debt already, there isn't enough money on the table to even think about it. Not to mention It would cause inflation. If everyone has more money all the sudden, wouldn't prices go up?
On Steemit however, Steem Basic Income is a good idea because you have to invest to get into it. I would compare to investment for the future, or a sort of annuity. No one is proposing right now to give these shares to everyone, however when you buy one you necessarily sponsor another person, which adds a nice element of kindness into the mix.